1. Field of the Invention
The invention herein relates to an improved structure high speed zigzag stitch industrial-use sewing machine in which a vertically extending, mailbox-shaped elevated material feed needle plate platform (Post Bed) structure is disposed below the needle holder of the sewing machine and, furthermore, the drive mechanism of the revolving shuttle and the material feed dog plate are situated in the interior section of the elevated material feed needle plate platform (Post Bed), with modifications afforded by the said drive mechanism enabling a size reduction of the interior section of the columnar elevated material feed needle plate platform (Post Bed) and variations in the type of stitches sewn by the sewing machine are governed by a pattern cam; the said mailbox-shaped elevated material feed needle plate platform (Post Bed) structure especially provides for wider applications than conventional level platform-type material feed needle plates which are incapable of easily sewing across concave, convex, and other irregular contours of objects being processed; as such, the present invention is not only capable of various types of zigzag stitching, but also provides for the sturdier sewing and more attractive appearance of finished objects, while increasing the value and product quality and productivity of sewing machines in this category of industrial equipment.
2. Description of the Prior Art
Referring to FIG. 7, a conventional level platform-type sewing machine structure, the sewing machine B has disposed at its bottom section (below the needle holder B6) a level platform-type material feed needle plate base B7 structure and, as indicated in FIG. 1 and FIG. 2, a dog base plate B71 is situated at the interior section of the material feed needle plate base B7 which facilitates the installation of a material feed dog B72 at the top section of the dog base plate B71, and since one end of the dog base plate B71 is conjoined to an eccentric shaft B11 at the tail end of another drive shaft B1xe2x80x2 of the bottom panel and the other end is conjoined to a rocker arm B74, when the drive shaft B1xe2x80x2 is driven by the belt C and rotates along with the drive shaft B1, this initiates the movement of the dog base plate B71 following the repeated path shown in FIG. 3 and, furthermore, there is a press foot B75 at the upper extent of the material feed needle plate base B7 and when the dog base plate B71 ascends, the material feed dog B72 and the press foot B75 grasp the object being processed D between them such that the object being processed D becomes taut, at which time the dog 72 moves forward and backward (in the direction of the operator) along with the dog base plate B71 and after the object being processed D is pulled a given distance, the dog base plate B71 descends and releases the object being processed D, and then the dog base plate B71 moves forward and backward to the other side such that when the dog base plate B71 ascends once again and contacts the object being processed, the repetitive said routine completes the sewing action of the needle holder B6; furthermore, a pattern cam A structure is situated inside the head of the sewing machine B and the pattern cam A is coupled to a transverse main shaft B1 and rotates along with a main shaft B1; an idler wheel fixture B3 rests against the pattern cam A and is linked to a needle holder fixture B5 via a connecting rod B4 such that when the main shaft B1 of the sewing machine B drives the needle holder B6 upward and downward, the pattern cam A is thus rotated by the transverse shaft B2 which causes the idler wheel fixture B3 to move following the sinusoidal surface of the pattern cam A and the connecting rod B4 to repeatedly swing the needle holder fixture B5 leftward and rightward, while the needle holder B6 of the sewing machine B moves upward and downward to sew the object being processed to collectively generate a left and right transverse movement and thereby effectively accomplish a variable zigzag stitch as the object being processed is conveyed forward.
In addition, a revolving shuttle B8 structure is disposed within the interior section of the material feed needle plate base B7, the revolving shuttle B8 consisting of a connected drive mechanism that is driven into rotation by the drive shaft B1xe2x80x2 such that as the needle holder B6 descends, the thread at the inner section of the revolving shuttle B8 and in the needle B61 at the bottom end of the needle holder B6 is manipulated in a stitching routine that achieves the sewing of the object being processed D; furthermore, since the pattern cam A varying the sewn stitching is situated inside the material feed needle plate base B7 of the said conventional sewing machine, the drive mechanism within the interior section is occupies a space of considerably large dimensions and, furthermore, the other drive shaft B1xe2x80x2 rotating along with it in the bottom panel can only be accommodated in a level platform-type design arrangement; however, with regard to the physical characteristic of the object being processed, the level platform-type material feed needle plate base has no positions for a completely flat posturing and cannot be utilized for sewing and finishing irregularly contoured items such as joint guards, footwear, and other convex or concave planes and, therefore, is not only incapable of maintaining product quality, but leads to decreased productivity as well as product quality.
Therefore, the improved structure high speed zigzag stitch industrial-use sewing machine of the invention herein features a vertically extending, columnar elevated material feed needle plate platform (Post Bed) structure disposed below the needle holder of the sewing machine and, furthermore, the drive mechanism of the revolving shuttle and the material feed dog plate are situated in the interior section of the elevated material feed needle plate platform (Post Bed), with variations in the type of stitches executed by the sewing machine governed by a pattern cam; the elevated material feed needle plate platform (Post Bed) structure especially provides for wider applications than conventional level platform-type material feed needle plates which are incapable of easily sewing across the concave, convex, and other irregular contours of objects being processed; if such a columnar elevated needle plate platform is utilized, not only would the embellishing of concave, convex, and other irregular contours be possible, but the various types of zigzag stitching afforded would also provide for the sturdier sewing and a more attractive appearance of finished objects, while increasing the value and product quality and productivity of sewing machines in this category of industrial equipment, and this is the primary objective of the invention herein.
Another objective of the improved structure high speed zigzag stitch industrial-use sewing machine invention herein is the inclusion of a vertical base plate extending upward from the top section of a dog base plate and, furthermore, a vertically oriented slot is formed in the center section of the vertical base plate and a horizontally oriented slot is formed in bottom section of the vertical base plate, with a sliding block respectively situated in the each of the vertically oriented and horizontally oriented slots, such that the vertical base plate is capable of sliding upward and downward as well as swing forward and backward following the articulation of the sliding blocks and slots; thus, when the dog base plate moves, the vertical base plate moves along with it synchronously, thereby enabling the material feed dog at the top section to complete a zigzag stitch as the material is being fed through; and the material feed structure of the original level platform-type material feed needle plate base can be extended into the interior section of the mailbox-shaped, elevated material feed needle plate platform embodiment of the present invention.
Yet another objective of the improved structure high speed zigzag stitch industrial-use sewing machine invention herein is the inclusion of a vertical drive shaft linked to a drive mechanism of the bottom panel that transports the revolving shuttle close to the lower position of the columnar elevated material feed needle plate platform (Post Bed) and, furthermore, in synchronization with a rotating lower drive shaft such that the revolving shuttle structure of the original level platform-type material feed needle plate base can be extended into the interior section of the mailbox-shaped, elevated material feed needle plate platform (Post Bed) embodiment of the present invention.
Still another objective of the improved structure high speed zigzag stitch industrial-use sewing machine invention herein is the inclusion of a skirt plate seating recess formed in the end surface of a pattern mounting base where the pattern cam is sleeved onto a transverse shaft for the placement of a skirt plate into the said skirt plate seating recess and, furthermore, screws are utilized to fasten the skirt plate; in addition, the skirt plate is assembled to a sighting block that is first mounted on the said transverse shaft and when the sewing machine is being assembled and set up, after the calibration of the pattern cam and an eccentric idler wheel is completed as well as the alignment of a locating pin and a locating hole between the sighting block and the skirt plate, this provides for the rapid configuring of the pattern cam as well as the rapid and accurate sleeving of the pattern cam onto the transverse shaft which enables convenient pattern cam replacement and, furthermore, reduces the technical requirements of the operating personnel.